Spectacle lenses can be corrective or non-corrective; spectacle lenses can also be prescription or non-prescription. The spectacle lenses can be made for use in clear eyeglasses or tinted eyeglasses (for example, sunglasses). Spectacle lenses may include variable power across their surface area. In particular, such spectacle lenses are, for example, known as bifocals, progressives et cetera.
The range of spectacle lenses offered has become ever greater and more varied in recent years. New materials, production methods, coating and finishing processes enable the manufacturer to offer spectacle lens products that are tailored even more to the individual needs of the customer.
In the past, the base materials or the materials of the substrate spectacle lenses were predominantly made from mineral glasses, in particular crown glasses (Abbe dispersion number>55) and flint glasses (Abbe dispersion number<50). In the meantime, spectacle lenses from a multiplicity of organic materials have become available. Typical organic materials are diethylene glycol bisallyl carbonate or allyl diglycol carbonate (ADC), which are sold by the company PPG Industries under the brand name “Columbia Resin 39” or “CR 39”, higher refractive thermosetting polymer materials, such as for example the polythiol urethanes sold under the trade names MR-7, MR-8, MR-10 of the company Mitsui Chemicals (the abbreviation “MR” stands here for “Mitsui Resin”), polymethylmethacrylate (abbreviation: PMMA) or polycarbonate.
Spectacle lenses may include coatings. The optical coating of a spectacle lens may include an antireflective coating, a reflective coating, a hard coating, a dirt-repelling coating, a coating preventing or reducing fogging and a coating with an antistatic effect. Finally, there are coatings with a polarizing effect and coatings that produce a desired color impression. Each of these coatings may be formed by one or more individual optically transparent layers. Examples can be taken from the documents WO 10/109154 A1, WO 01/55752 A1 and DE 10 2008 041 869 A1.
A plurality of publications and patent documents deal with the task to reduce the impact of blue light, ranging in wavelength from approximately 400 nm to approximately 500 nm, having been identified as contributing cause of AMD (age related macular degeneration). In particular, United States patent application publication 2007/0216861 A1 discloses an ophthalmic lens blocking wavelengths of the electromagnetic spectrum between about 400 and about 500 nm and transmitting at least 85% of wavelengths of the electromagnetic spectrum outside between about 400 and about 500 nm. This document discloses that the known techniques to block blue light wavelengths include absorption, reflection, interference, or any combination thereof. According to one technique described therein, a lens may be tinted/dyed with a blue blocking tint, such as BPI Filter Vision 450 or BPI Diamond Dye 500, in a suitable proportion or concentration. The tinting may be accomplished, for example, by immersing the lens in a heated tint pot containing a blue blocking dye solution for some predetermined period of time. According to another technique which is also disclosed in United States patent application publication 2007/0216861 A1, a filter is used for blue blocking. The filter could include, for example, organic or inorganic compounds exhibiting absorption and/or reflection of and/or interference with blue light wavelengths. The filter could include multiple thin layers or coatings of organic and/or inorganic substances. Each layer may have properties, which, either individually or in combination with other layers, absorbs, reflects or interferes with light having blue light wavelengths. Rugate notch filters are one example of blue blocking filters. Still another technique for blue blocking disclosed in United States patent application publication 2007/0216861 A1 is the use of multi-layer dielectric stacks. Multi-layer dielectric stacks are fabricated by depositing discrete layers of alternating high and low refractive index materials. Similarly to rugate filters, configuration parameters such as individual layer thickness, individual layer refractive index, and number of layer repetitions determine the performance parameters for multi-layer dielectric stacks.
Another patent document dealing with materials and methods for mitigating the harmful effects of blue light is WO 2015/171781 A1. This document proposes a spectacle lens having a front face and a rear face. The spectacle lens including a substrate having a front surface and a rear surface; and a first multilayer dielectric coating disposed on the front surface of the substrate. The front face of the spectacle lens exhibits a maximum reflectance in the visible spectrum at a wavelength of from 430 nm to 470 nm, wherein the front face of the optical lens exhibits a reflectance of from 2% to 18% reflectance at 400 nm, of from 5% to 30% reflectance at 450 nm, and of from 3% to 20% reflectance at 500 nm. The front face of the optical lens shall exhibit a reflectance spectrum having a full width at half maximum of at least 75 nm. The transmission properties of the spectacle lens are not discussed therein.
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